1st |Asus
2nd |His or msi
To be honest most use the same pcb and parts there is a small few that use there own design even there own bios settings clock speeds etc. but most just use the same and put there name on it.
i have a power color 3870x2 and it looks and works the same as any of the above.

i think the visiontek is same as the above with just the visiontek name on it.

Visiontek has a limited lifetime warranty on them, but not sure how they are for RMA's if there are issues. I have heard nothing but good things for HIS as far as quality. Asus should be good also (3 year warranty) as well as Saphire (2 year warranty - only through the original place of purchase though).

As of now all the board vendors incorporate the same reference PCB and cooler design barring one model from ASUS that has a non-reference design. It boils down to which company better offers end-user support, warranty policies, package contents and above all, price. Among the reference design cards, I'd suggest HIS, it has a little more to its package contents, a mini-screwdriver and HIS is quite an established board vendor. VisionTek is good too, like I said it boils down to some very minor issues barring warranty policies which is crucial. There are some non-reference designs in the works from the likes of Sapphire (their Atomic fluid-cooled card) and the ASUS card.